Role of p53 Missense Mutations on Tumorigenesis in Vivo

项目摘要 癌症是一组复杂、异质和毁灭性的疾病;然而，一个共同的主题是 TP 53肿瘤抑制基因的复发和高频突变。与其他肿瘤相比 抑制子，大多数TP 53改变是错义突变，并且这些表现出功能获得表型， 都依赖于转录重组该建议的重点是p53错义突变在 三阴性乳腺癌（TNBC）。乳腺癌是一种广泛分布的恶性肿瘤，占所有乳腺癌的15%。 全球女性癌症死亡人数。80-88%的基底细胞样乳腺癌，其中大多数是TNBC， TP 53肿瘤抑制基因突变。我们最近培育出了第一只基因工程老鼠 由p53错义突变驱动的体细胞乳腺癌模型。这个条件模型代表了一个主要的 因为它从内源基因座表达突变型p53并在基质中维持野生型p53， 免疫系统此外，我们的模型忠实地模仿了人类TNBC的组织学，并开发出具有以下特征的TNBC： 一年的潜伏期此外，在这些小鼠中，用CRISPR-Cas9缺失突变型p53导致肿瘤细胞生长。 退化和增加的存活率，表明乳腺肿瘤对突变型p53上瘾。另外我们 见肿瘤消退后T淋巴细胞浸润增加。在这项研究中，我们建议了解 由体细胞p53驱动突变引发的TNBC生物学，并确定为什么这些肿瘤依赖于 突变型p53。这项工作结合了我们优雅的和疾病相关的TNBC小鼠模型， ART基因组分析，以全面了解突变型p53驱动乳腺癌的潜在机制 癌此外，我们将使用最近从我们的模型中获得的细胞系，这些细胞系也对突变型p53上瘾。 作为一个平台，进行功能基因组学筛选，以确定这些癌症的新弱点。 基于免疫的疗法彻底改变了癌症护理。因此，为了有效地促进突变型p53定向 因此，需要全面了解免疫景观和反应。由于我们 体细胞乳腺模型独特地保留了WT p53微环境和免疫区室， 理想的位置，以检查免疫应答突变p53定向治疗。我们的具体目标是：目标 1.为了了解p53缺失小鼠与突变小鼠中乳腺癌发生的潜在生物学机制， 我们将进行全外显子序列分析。为了确定导致成瘾的分子途径， 突变型p53乳腺癌，我们将进行体细胞p53 R172 H乳腺肿瘤的RNA-seq分析， 而不缺失突变型p53。目标2.为了确定突变型p53下游的分子通路， 对于使用CRISPR/Cas9功能筛选的肿瘤维持至关重要。目标3。去理解和利用 对乳腺癌中突变型p53的治疗性抑制的免疫应答。因为我们的条件鼠标 模型与人类散发性肿瘤共享潜在的分子病理学，它将更能预测 人类对药物的反应，因此是临床前测试中的有价值的工具。

Project Summary Cancer is a collection of complex, heterogeneous, and devastating diseases; however, one common theme is recurrent and high-frequency mutations in the TP53 tumor suppressor gene. In contrast to other tumor suppressors, most TP53 alterations are missense mutations and these exhibit gain-of-function phenotypes that are dependent of transcriptional rewiring. This proposal is focused on the role of p53 missense mutations in triple negative breast cancer (TNBC). Breast cancers are widespread malignancies representing 15% of all cancer deaths in women worldwide. 80-88% of basal-like breast cancers, the majority of which are TNBC, have mutations in the TP53 tumor suppressor. We have recently developed the first genetically engineered mouse model of somatic breast cancer driven by p53 missense mutations. This conditional model represents a major advance as it expresses mutant p53 from the endogenous locus and maintains wild-type p53 in the stroma and immune system. Moreover, our model faithfully mimics the histology of human TNBC, and develops TNBC with a one year latency. Moreover, in these mice, deletion of mutant p53 with CRISPR-Cas9 results in tumor regression and increased survival, indicating that the breast tumors are addicted to mutant p53. In addition, we see increased infiltration of T lymphocytes upon tumor regression. In this study, we propose to understand the biology of TNBC initiated by a somatic p53 driver mutation and determine why these tumors are addicted to mutant p53. This work combines our elegant and disease relevant mouse models of TNBC with state-of-the- art genomic profiling to comprehensively understand the mechanisms underlying mutant p53 driven breast cancer. Moreover, we will use cell lines recently derived from our model that are also addicted to mutant p53 as a platform to undertake a functional genomics screen to identify novel vulnerabilities in these cancers. Immune based therapies have revolutionized cancer care. Therefore to effectively advance mutant p53 directed therapies, a comprehensive understanding of the immune landscape and response is needed. Since our somatic breast model uniquely retains a WT p53 microenvironment and immune compartment, we are in an ideal position to examine the immune response to mutant p53 directed therapies. Our specific aims are: Aim 1. To understand the underlying biology that drives breast cancer development in p53-null versus mutant mice, we will perform whole exome sequence analyses. To identify the molecular pathways that lead to addiction of mutant p53 breast cancers, we will perform RNA-seq analyses of somatic p53R172H breast tumors with and without deletion of mutant p53. Aim 2. To determine the molecular pathways downstream of mutant p53 that are essential for tumor maintenance using CRISPR/Cas9 functional screens. Aim 3. To understand and exploit the immune response to therapeutic inhibition of mutant p53 in breast cancer. Because our conditional mouse model shares the underlying molecular pathology with human sporadic tumors, it will be more predictive of human responses to drugs, and thus a valuable tool in preclinical testing.